We have found a newly discovered peptide, galanin, to be widely distributed in the rat central nervous system (CNS). All cells in the locus coeruleus contain galanin and therefore coexist with norepinephrine-containing nerves that project to the cortex, hippocampus, thalamus, parts of the hypothalamus and spinal cord. The coexistence of galanin and norepinephrine in catecholaminergic nerves suggests that galanin might be involved in a neuroregulatory role at the site of norepinephrine action.